I've been researching this since I bought it. Haven't found a positive ID on this yet. However, with this being said I have come to some conclusions. First and foremost, I don't believe this to be Avon from Cincinatti for a handful of reasons.
As much as I would love to be believe this is AVON, I have to go with my gut feeling. And following your gut is always a good iea for any collector.
1. I don't believe this is an inkwell.
2. This isn't what I would believe to be a piece of pottery from this AVON of Cincinatti pottery.
3. Many, many potteries have used the name Avon throught the years. The name of the pottery or the design.
4. Researching through AVON collectibles online and in books they have used a backmark very similar to the item in question and similar to the AVON from Cincinatti. And others come close. The other avon I'm speaking of the everyday avon from your local representative. The perfume and cologne AVON.
5. Although the mark looks close to the AVON from Cincinatti and I've had people agree that it is, I have to go with my gut instinct. This has done well for me over the years. And my gut says it isn't.

If I come across who really made this I will post the info.
And I'm sure alot of pottery gets ID as the one from Cincinatti. Nature of the game. Hope can play alot when placing an ID on an item sometimes.